Scientific Method
This is the variable that scientist intentionally changes test it's affects on the experiment.
What is the independent variable?
In a CER, this part uses observations, measurements, or data from the experiment to support the claim.
What is the evidence?
A person has brown eyes, curly hair, and a fast heartbeat after running. Which of these is not an external trait?
What is a fast heartbeat?
Which of these is a phenotype: Bb, brown eyes, heterozygous, or dominant allele?
What is brown eyes?
A student tests whether a trait is inherited by comparing family members. They notice that parents and children have similar traits and conclude:
"Children always have the exact same traits as their parents."
Why is this conclusion not scientifically accurate?
What is because children inherit combinations of traits from their parents, so they may share some traits but not all traits?
During an experiment, a student accidentally skips recording the data for one day. Which step of the scientific method was not completed correctly
What is collecting/recording data (or analyzing results)?
A student's claim says, "Plants grow best in sunlight," but their evidence discusses how much water the plants received. What is the biggest problem with this CER?
What is the evidence does not support the claim?
A student says, "Blood type is an external trait because everyone has one." Identify the mistake in the student's reasoning.
What is blood type is an internal trait because it cannot be observed by simply looking at a person?
A trait is controlled by alleles A and a. An organism has the genotype Aa. A student says the recessive trait will appear because the organism has an "a." What is the student misunderstanding?
What is the dominant allele masks the recessive allele when both are present?
A student says, "The recessive trait disappeared from the population because the dominant trait covered it up." Another student disagrees. Who is correct and why?
What is the second student is correct because a dominant allele can hide the expression of a recessive allele, but it does not remove the recessive allele from the organism or population?
Why is it important to test only one variable at a time.
What is to know which variable caused the results?
A student's CER includes a clear claim, accurate data, and an explanation of the science. However, the evidence only comes from one trial. What is one limitation of the student's scientific report?
What is that one trial does not provide enough evidence, additional trials would make the conclusion more reliable?
A scientist records a person's hair color, eye color, and freckles. What do all three observations have in common?
What is they are all external traits?
This term describes an organism with two identical alleles, such as TT or tt.
A plant has the genotype Tt. This term describes its allele combination.
What is homozygous?
What is heterozygous?
Two plants both have red flowers. The scientist knows red is dominant. Plant A has genotype RR, but Plant B's genotype is unknown. Can the scientist determine Plant B's genotype by looking at the flowers? Explain.
What is no, because Plant B could be RR or Rr and both would have red flowers?
Two students test the same hypothesis but get different results. What should they do before deciding which result is correct
What is repeat the experiment or perform more trials?
A student concludes that all plants grow faster with fertilizer after testing only one type of plant. What is wrong/incorrect about this conclusion?
What is because the claim is to broad and the evidence only supports the type of plant that was tested?
Two students disagree about whether body temperature is an internal or external trait. One says it's external because it can be measured on the skin. Which student is correct and why?
What is the student who says it is an internal trait, because it reflects what is happening inside the body?
A student says, "The dominant allele is the one that an organism inherited from its mother." Why is this incorrect?
What is dominance is determined by how alleles are expressed, not which parent they came from?
A scientist discovers a new trait in plants. A purple flower color is dominant (P) and white flower color is recessive (p). A flower has purple petals. The scientist writes in a report:
"Claim: This flower has the genotype PP.
Evidence: The flower is purple.
Reasoning: Purple is dominant, so the flower must have two dominant alleles."
What is the biggest mistake in this scientific report?
What is the scientist cannot determine the genotype from the phenotype alone because the flower could be PP or Pp?
: A scientist's hypothesis is supported by one experiment. Can the scientist now say the hypothesis is proven? Why or why not?
What is no hypotheses are supported by evidence but should be tested multiple times because one experiment does not prove them true?
Claim: Salt affects plant growth.
Evidence: The plant with salt grew 3 cm, while the plant without salt grew 9 cm.
Reasoning: Plants need water to grow, and too much salt can make it harder for plants to absorb water.
If you were grading this CER, which section could be strengthened the most, and how?
What is the evidence, because it should include more than one trial or additional data to better support the claim?(Students could also justify strengthening the reasoning if they explain why.)
A student says, "Anything you can see is a trait." Why is that statement not always correct?
Because some visible characteristics, like a cast, a tan, or dyed hair, are not inherited human traits.
A pea plant has the genotype Gg. Without changing the letters, how could you describe this plant using two genetics vocabulary words?
What is heterozygous and dominant (shows the dominant trait)?
A scientist studies a population of rabbits. Black fur (B) is dominant and white fur (b) is recessive.
The scientist observes:
The scientist concludes:
"Because black fur is dominant, most rabbits in this population must have the BB genotype."
Is this conclusion supported by the evidence? Explain.
What is no; phenotype alone cannot determine genotype, and black rabbits could be BB or Bb. More genetic information would be needed.